An epitaxial silicon wafer is provided in which an epitaxial layer is grown on a silicon wafer having a plane inclined from a {110} plane of a silicon single crystal as a main surface. In the silicon wafer for growing the epitaxial layer thereon, an inclination angle azimuth of the {110} plane is in the range of 0 to 45 degrees as measured from a orientation parallel to the {110} plane toward a direction. With such an arrangement, LPDs of 100 nm or less can be measured from a {110} wafer that has a carrier mobility (including the hole and electron mobilities) higher than that of a {100 } wafer. Also, surface roughness degradation in the {110} wafer can be suppressed. Also, the surface state of the {110} wafer can be measured. Further, a quality evaluation can be performed on the {110} wafer.